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Home , Cucurbita maxima, Cucurbita pepo, Summer squash

HORTSCIENCE 35(2):281–285. 2000. Materials and Methods

Pumpkin evaluations were con- Evaluation of for ducted at the Coastal Research and Education Center, Charleston, S.C., on Yonges loamy Powdery and Downy Mildew fine sand (fine-loamy, mixed, thermic, Typic Albaquults). The experiments were random- Resistance, Virus Tolerance, and Yield ized complete blocks with three replications in 1996 and four replications in 1997. Each plot Anthony P. Keinath1 and Virginia B. DuBose2 was a single row of eight . In previous cultivar evaluations, Department of Pathology and Physiology, Clemson University, Coastal with different maturity dates were all seeded Research and Education Center, Charleston, SC 29414-5332 or transplanted and harvested at the same time, which may not provide an equitable yield Additional index words. pepo, , papaya ringspot virus, comparison among cultivars (Bost et al., 1991; Pseudoperonospora cubensis, Sphaerotheca fuliginea, , Precheur et al., 1994, 1998). In our experi- yellow mosaic virus ments, three seeding and transplanting dates Abstract. Twenty-six cultivars and two numbered selections of L. pumpkin were used so that all cultigens reached matu- and four cultivars of C. maxima Duchesne pumpkin were evaluated in field experiments rity at the same time, because harvest date is in 1996 and 1997 in Charleston, S.C. The four C. maxima cultivars (‘Mammoth Gold’, ‘Big important for marketing pumpkins. Thirty- Max’, ‘Rouge Vif d’Etamps’, and ‘Lumina’) and three C. pepo cultigens (HMX 6686, HMX two pumpkin cultigens were separated into 6688, and Magic Lantern) had lower powdery mildew [Sphaerotheca fuliginea three groups based upon days to maturity (Schlechtend.:Fr.) Pollacci] severities than did the other C. pepo cultivars. Overall, C. (DTM) as indicated by seed company descrip- maxima cultivars also had less foliage showing virus symptoms and less downy mildew tions. Long- (110-120 d), mid- (100-105 d), [Pseudoperonospora cubensis (Berk.& M.A. Curtis) Rostovzev] than did C. pepo cultigens. and short-season (85-95 d) pumpkins were Mid- and long-season cultigens of both species (≥100 days to maturity) produced a greater seeded on 11 June, 21 June, and 1 July 1996, number of marketable-quality than did short-season cultigens. Cucurbita maxima respectively, and 27 June, 8 and 18 July 1997, and C. pepo produced similar numbers of marketable fruit; however, more potential respectively. Seedlings within each maturity marketable yield was possible in C. maxima since most fruit were affected by virus. The C. date were transplanted to the field 10 or 11 d pepo cultigens Spookie, HMX 6686, and Spooktacular produced the greatest numbers of after seeding, so that the harvest dates would marketable fruit. In general, no cultigens were well-adapted to the growing conditions of coincide. Plants were spaced 0.9 m apart within the humid coastal plain of the southeastern United States. rows in 1996 and 1.2 m apart in 1997. Plots were separated by 3.0 m of space within rows. Pumpkin can be a profitable crop when mation is available on management of pump- Row spacing was 1.8 m on bed center and grown for the Halloween market. Because of kin diseases in the southeastern coastal plain. every other row was planted. Transplants that the high potential return per hectare, pumpkin Minimizing pesticide inputs may improve the died within 1 week of transplanting were re- is particularly suited for growers with limited profit margin of the crop (Olson et al., 1995), placed so that all plots contained eight plants. acreage or those located near urban areas. To although some fungicide must be applied to In 1996, but not in 1997, were moved yield well under current management prac- prevent premature defoliation and senescence. into the 1.8-m-wide area until late in the sea- tices, pumpkin requires expensive inputs, such Careful selection of pumpkin cultivar can son because of sprayer limitations. as white or black polyethylene mulch and reduce disease severity. For example, without Before planting, 900 kg·ha–1 of 10N–4.4P– regular insecticide and fungicide applications fungicide applications, ‘’ had less 8.3K (1996) or 670 kg·ha–1 of 15N–0P–12.5K (Kemble et al., 1997). Because pumpkin has a downy and powdery mildew than seven other fertilizer (1997) were broadcast before raised long growing season (90 to 120 d) and is cultivars (Bost et al., 1991). The heirloom beds were shaped and covered with white-on- planted later than most warm-season vegetable cultivar Rouge Vif d’Etamps had significantly black polyethylene mulch. Plots were side- crops, vines must be protected from several less powdery mildew than nine other cultivars dressed in the alleys on 25 July in both years foliar pathogens. In the southeastern United (Precheur et al., 1994). However, both of these with 220 kg·ha–1 10N–4.4P–8.3K. For weed States, both downy mildew and powdery mil- cultivars are C. maxima, and do not produce control, bensulide (S-2-benzenesulfonamidoethyl dew reduce yields (Bost et al., 1991; Shoe- typical jack-o-lantern–type fruit. Conse- O,O-di-isopropyl phosphorodithioate ) (3.4 maker, 1994). In addition, viruses such as quently, this resistance is not as useful for kg·ha–1 a.i.) was applied preplant to alleys in papaya ringspot virus (PRSV), watermelon commercial producers as resistance or toler- 1996 and clomazone {2- [(2-chlorophenyl) mosaic virus (WMV), and zucchini yellow ance would be in C. pepo cultivars. Recently, methyl]-4,4 dimethyl-3-isoxazolidinone} (1.1 mosaic virus (ZYMV) infect C. pepo and C. pepo lines with resistance to powdery mil- kg·ha–1 a.i.) was broadcast preplant in 1997. reduce marketable yields in this region dew have been evaluated in the northeastern Sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2- (Schultheis and Walters, 1998). Little infor- United States (McGrath and Sieczka, 1997), (ethylthio) propyl]-3-hydroxy-2-cyclohexene- but their yield, fruit quality, and resistance to 1-one} (0.31 kg·ha–1 a.i.) also was applied to other diseases under southeastern conditions control grasses in 1997. To manage insects, are not known. No commercially available maximum labeled rates of esfenvalerate [(S)- Received for publication 26 Feb. 1999. Accepted for α publication 25 Aug. 1999. Technical contribution cultivars have resistance to viral diseases, al- -cyano-3-phenoxybenzyl (S)-2-(4-chlorophenyl)- no. 4472 of the South Carolina Agriculture & For- though the cultivars Autumn Gold and Big 3-methylbutyrate] or endosulfan (6,7,8,9,10,10- estry Research System, Clemson. We gratefully Autumn have the precocious yellow gene (Py), hexachloro-1,5,5a,6,9,9a-hexahydro-6,9- acknowledge Warren May III for technical assis- which masks color-breaking caused by virus methano-2,4,3-benzodioxathiepin 3-oxide) tance and Ted Superak, Harris-Moran Seed Co., for infection (Snyder et al., 1993). were applied in alternate weeks from planting providing numbered, powdery mildew-resistant se- The objective of this study was to evaluate until harvest both years; in 1997, Bacillus lections. Salaries were supported in part by Hatch commercially available pumpkin cultivars and thuringiensis and permethrin [3-phenoxybenzyl Project SC01628. The cost of publishing this paper advanced numbered selections for resistance (1RS)-cis,trans-3-(2,2-dichlorovinyl)-2,2- was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must to powdery mildew and potential for yield dimethylcyclopropanecarboxylate] also were be hereby marked advertisement solely to indicate under the humid growing conditions of the used. In 1996, the fungicides chlorothalonil this fact. coastal plain of the southeastern United States. (tetrachloroisophthalonitrile) - triadimefon [1- 1Associate Professor. e-mail: [email protected] Tolerance to virus infection and downy mil- (4-chlorophenoxy)-3,3-dimethyl-1-(1H- 2Agriculture/Animal Associate II. dew also was assessed. 1,2,4,-triazol-1-yl)-2-butanone] (1.7 or 2.5

HORTSCIENCE, VOL. 35(2), APRIL 2000 281 BREEDING, CULTIVARS, ROOTSTOCKS, & GERMPLASM RESOURCES kg·ha–1 a.i. chlorothalonil plus 0.09 or 0.13 on species, days to maturity, fruit size, growth with the lowest ratings (most resistant) were kg·ha–1 a.i. triadimefon) or maneb (manganese habit, and commercial type. HMX 6688, Magic Lantern, and HMX 6686, ethylenebisdithiocarbamate) (1.3 or 1.8 kg·ha– and the C. maxima cultivars Rouge Vif 1 a.i.) plus benomyl [methyl 1-(butylcarbamoyl) Results d’Etamps and Lumina. benzimidazol-2-ylcarbamate] (0.14 or 0.28 Downy mildew. Downy mildew was present kg·ha–1 a.i.) were applied in alternate weeks to Powdery mildew. Powdery mildew was both years and, similar to powdery mildew, manage powdery mildew, and metalaxyl [N- the most prevalent foliar disease in both years, progressed faster in 1996 than in 1997. How- (2,6-dimethylphenyl)-N-(methoxyacetyl)-DL- was more severe in 1996 than in 1997, and, on ever, downy mildew increased late in the sea- alanine methyl ester] - chlorothalonil (0.20 or susceptible cultivars, was not completely con- son in 1997 and contributed to foliage senes- 0.30 kg·ha–1 a.i. metalaxyl plus 1.6 or 2.4 trolled by alternate-week fungicide applica- cence. The highest mean mildew rating on 19 kg·ha–1 a.i. chlorothalonil) or fosetyl-alumi- tions (Table 1). In both years, C. maxima Aug. 1996 was 54% for ‘Rocket,’ but on 5 num [aluminum tris(O-ethyl phosphonate)] cultivars had less powdery mildew overall Sept. 1997, the highest rating was only 3.6% (1.8 or 4.5 kg·ha–1 a.i.) were applied in alter- than did C. pepo cultigens (P = 0.0001). for both ‘Connecticut Field’ and ‘Howden’ nate weeks to manage downy mildew. All When ratings for both years were com- (Table 1). In both years, C. maxima was less fungicides were used at lowest labeled rates bined and analyzed together, there was a sig- susceptible to mildew than was C. pepo (P ≤ (first rate given above) from 17 July until 3 nificant genotype × year interaction (P ≤ 0.001). ‘Big Max’ and ‘Mammoth Gold’, both weeks before harvest, when maximum labeled 0.0001), probably because a few cultivars, C. maxima cultivars, were among the culti- rates (second rate given above) were substi- such as ‘Big Autumn’, ‘Oz’, and ‘Tom Fox’, gens with the lowest ratings both years. tuted. From 16 July to 8 Aug. 1997, 1.8 kg·ha– were severely diseased one year but had less Virus symptoms. Leaves of all cultivars 1 a.i. maneb or 1.6 kg·ha–1 a.i. chlorothalonil mildew the other year (Table 1). However, were distorted and mottled with virus symp- was applied weekly to control foliar patho- despite this interaction, ‘Wizard,’ ‘Happy toms by the end of August in both years. In gens. From 13 Aug to 26 Sept., fungicides Jack,’ and ‘Spookie’ were ranked among the 1996, ZYMV and PRSV were detected in all were applied as in 1996 but maximum rates most susceptible cultivars in both years, and samples and WMV was detected in half of the were used the entire season. ‘Magic Lantern’ and ‘Lumina’ had low levels samples. In 1997, samples of distorted leaves Severity of powdery and downy mildew of mildew both years. Overall, the cultigens were positive for both ZYMV and PRSV, was rated in all plots with the Horsfall–Barratt scale (Horsfall and Barratt, 1945) (1 = 0% leaf Table 1. Powdery mildew severity on 26 Cucurbita pepo and four C. maxima pumpkin cultigens in 1996 and surface area diseased to 12 = 100% of leaf 1997. surface diseased) four times at 7- to 10-d Powdery mildew Downy mildew Foliar virus intervals beginning 1 week after the first trans- severity (%)z severity (%)y severity (%)x planting. Because identifying individual cu- Cultigen 1996w 1997 1996w 1997 1996 1997 curbit viruses is difficult based on foliar symp- toms (Zitter et al., 1996), an overall rating for C. pepo Appalachian 39.5 a–ev 46.8 a–d 12.2 bc 1.5 a–d 93.3 a–e 93.6 a–c percentage of leaf area affected with virus Autumn Gold 45.1 a–c 23.8 b–g 12.2 bc 0.4 b–d 96.4 a–d 78.2 a–d symptoms was made with the Horsfall- Barratt Big Autumn 62.5 a 8.3 gh 31.2 a–c 0.1 cd 91.5 a–e 92.5 a–d scale on 29 Aug. 1996 and 16 Sept. 1997. To Connecticut Field 24.8 b–g 49.2 a–c 12.2 bc 3.6 a 94.7 a–e 72.2 a–d identify which viruses were present in the Funny Face 45.8 a–c 47.1 a–d 37.5 ab 1.3 a–d 68.4 b–f 92.6 a–d fields, two and three composite foliage samples Ghost Rider 44.0 a–d 40.8 a–d 24.8 a–c 1.3 a–d 89.4 a–e 89.9 a–d in 1996 and 1997, respectively, were assayed HMX 6686u 10.7 f–h 0.1 i 18.5 a–c 0.8 a–d 94.0 a–e 85.5 a–d with enzyme-linked immunosorbent assay HMX 6688u 12.2 e–h 1.9 hi 20.2 a–c 1.1 a–d 96.9 a–d 85.4 a–d (ELISA) for cucumber mosaic virus, PRSV, Happy Jack 54.2 ab 55.6 a 21.7 a–c 0.8 a–d 95.5 a–e 99.3 a squash mosaic virus, WMV, and ZYMV. All Howden 39.5 a–e 50.5 ab 21.7 a–c 3.6 a 93.3 a–e 95.2 a–c Howden Biggie 31.2 a–f 30.9 a–f 12.2 bc 0.8 a–d 97.9 a–c 81.6 a–d fruit with at least 50% of the surface deep Jack of All Trades 24.1 b–g 20.8 c–g 26.5 a–c 1.1 a–d 84.0 a–e 89.8 a–d orange were harvested from each plot on 13 Jackpot 16.3 c–h 27.2 a–g 31.2 a–c 0.1 cd 92.4 a–e 78.2 a–d Sept. 1996 and on 23 and 30 Sept. and 7 Oct. Little Lantern 18.5 c–h 19.6 d–g 21.7 a–c 0.4 b–d 100 a 91.4 a–d 1997. Fruit were weighed and separated into Magic Lanternu 7.5 f–h 2.1 hi 21.7 a–c 2.1 a–c 95.5 a–e 94.3 a–c marketable and nonmarketable quality. Fruit Oz 62.5 a 19.6 d–g 31.2 a–c 1.3 a–d 98.7 ab 82.1 a–d considered marketable had firm flesh with no Pankow’s Field 30.0 b–f 23.9 b–g 24.8 a–c 1.9 a–c 77.4 a–f 76.9 a–d decay, intact, firm stems, and either no color- Pro Gold 500 68.4 a 23.9 b–g 24.8 a–c 0.4 b–d 94.7 a–e 72.9 a–d breaking or surface disfiguration due to vi- Pro Gold 510 45.1 a–c 27.1 a–g 24.8 a–c 0.7 a–d 95.7 a–e 86.6 a–d ruses (1996) or <20% surface area with virus Rocket 44.9 a–c 22.6 b–g 54.2 a 1.3 a–d 88.8 a–e 88.9 a–d Small 39.5 a–e 37.3 a–e 15.3 bc 1.5 a–d 96.7 a–d 98.0 ab symptoms (1997). Spirit 30.4 a–f 27.2 a–g 28.0 a–c 1.1 a–d 95.4 a–e 89.4 a–d Percentage of leaf surface area diseased Spookie 54.2 ab 53.1 ab 15.3 bc 2.1 a–c 97.9 a–c 87.9 a–d was calculated from the midpoints of the ranges Spooktacular 24.1 b–g 14.3 e–h 31.2 a–c 0.7 a–d 60.2 c–f 80.2 a–d represented by Horsfall-Barratt ratings Tallman 24.8 b–g 48.4 a–d 15.3 bc 2.1 a–c 93.6 a–e 58.6 cd (Horsfall and Barratt, 1945). Percent disease Tom Fox 24.8 b–g 50.5 ab 21.7 a–c 2.8 ab 98.0 a–c 85.5 a–d severity and yield data were subjected to analy- Trickster 15.0 d–h 28.5 a–g 43.8 ab 0.1 cd 98.9 ab 91.3 a–d sis of variance with PROC GLM of SAS Wizard 54.2 ab 59.8 a 31.2 a–c 2.8 ab 95.4 a–e 97.4 ab version 6.12 (SAS Institute, Cary, N.C.). All C. maxima data were checked for normality and equality Big Max 15.3 d–h 27.2 a–g 6.7 c 0.0 d 53.5 ef 67.1 b–d of variance before analysis; data for percent- Lumina 2.7 h 3.6 hi 18.5 a–c 0.7 a–d 58.5 d–f 50.0 d age of disease severity and number of fruit Mammoth Gold 24.8 b–g 22.6 b–g 6.0 c 0.1 cd 64.7 b–f 64.7 b–d were transformed to square-roots. The Waller– Rouge Vif d’Etamps 4.5 hg 11.8 f–h 18.5 a–c 0.1 cd 31.9 f 70.6 a–d Duncan k ratio t test was used to separate zPercentage of upper and lower leaf surface area covered with powdery mildew on 19 Aug. 1996 and 5 Sept. 1997, respectively. cultigen means, except for number of market- y able fruit in 1996, where Dunnett’s t test was Percentage of upper and lower leaf surface area covered with downy mildew on 19 Aug. 1996 and 5 Sept. 1997, respectively. used to determine which cultigens produced xPercentage of leaf surface area with virus symptoms on 29 Aug. 1996 and 16 Sept. 1997, respectively. mean numbers of fruit significantly >0. In wCultigen × year interaction significant at P ≤ 0.0001. addition, preplanned, single-degree-of-free- vMean separation within years by Waller–Duncan k ratio t test; k = 500 (approximates P = 0.01) for powdery dom contrasts were calculated to compare mildew and virus and k = 100 (approximates P = 0.05) for downy mildew. yields for different groups of cultigens based uCultigen with resistance to powdery mildew.

282 HORTSCIENCE, VOL. 35(2), APRIL 2000 whereas samples of leaves with mosaic were more total and marketable fruit in 1997 than in Vif d’Etamps’ and ‘Tallman’, produced fruit positive for only ZYMV; WMV was not de- 1996; however, ‘Spooktacular’, ‘Funny Face’, weighing more than the upper threshold for tected. Rankings of the cultigens based on ‘Oz’, and ‘Trickster’ produced more market- medium-sized fruit. By size class, mean fruit foliar virus symptoms differed in the 2 years able-quality fruit in 1996 than in 1997 (Table weights for cultigens with small (0.36 kg), (Table 1). In 1996, percentage leaf area with 2). HMX 6686 had the highest number of total medium (0.82 kg), and large (1.25 kg) symptoms was significantly less in ‘Rouge Vif fruit both years and ‘Spooktacular’ and also were very low in 1996. In 1997, weights d’Etamps,’ ‘Big Max,’ ‘Lumina,’ and ‘Spookie’ had the highest numbers of market- for the three size classes were similar to ex- ‘Spooktacular’ than in ‘Little Lantern,’ ‘Trick- able-quality fruit in 1996 and 1997, respec- pected values: 10.1 kg (range 22.1 to 5.3) for ster,’ and ‘Oz’. In 1997, ‘Lumina’ and tively. Among C. maxima cultivars, Rouge large-, 5.1 kg (range 12.6 to 2.0) for medium- ‘Tallman’ had significantly less foliage with Vif d’Etamps yielded the most total fruit both , and 1.8 kg (range 2.6 to 1.1) for small-fruited symptoms than did ‘Happy Jack,’ ‘Small years, but marketable yields were low for all cultigens. In both years, class means for the Sugar,’ and ‘Wizard.’ In both years, C. maxima four C. maxima cultivars. Most of the nonmar- three sizes differed significantly from each cultivars had fewer symptoms overall than did ketable fruits were disfigured with warts or other (P ≤ 0.01 in 1996 and P ≤ 0.0001 in C. pepo cultigens (P ≤ 0.0001). knobs or had uneven green-orange coloration 1997). Yield of fruit. Fruit numbers were low for due to virus infection. Comparison of classes of cultivars. Be- most cultivars in both years. In 1996, harvest Mean fruit weight. In 1996, mean fruit cause of the large number of cultivars exam- was ≈3 weeks earlier than anticipated because weights were uniformly low (Table 2). In ined in this study, means also were compared of accelerated foliage senescence. 1997, weights for 13 cultivars fell within the by classes of cultivars (Table 3). Cultivars Choanephora wet rot, caused by Choanephora ranges of expected values (<4.5, 4.5 to 9.1, and were assigned to classes according to species, cucurbitarum (Berk. & Ravenel) Thaxt., was ≥9.1 kg for cultigens with small, medium, and expected days to maturity, expected fruit size, observed on decaying young fruit in both years. large fruit, respectively) (Table 2). Five culti- growth habit ( or semi-bush) and type of Cultivars Autumn Gold, Happy Jack, and Tom vars expected to produce large fruit had fruit pollination (open-pollinated or ) (Tables Fox set no fruit in 1996, but all cultigens weights less than 9.1 kg and nine cultivars 1 and 2). Cucurbita maxima cultivars, as a except Big Autumn produced at least one fruit expected to produce medium-sized fruit had group, produced significantly higher numbers per plot in 1997. Most cultivars produced fruit weights <4.5 kg. Two cultivars, ‘Rouge of total fruit than did C. pepo cultigens in both

Table 2. Vine and fruit characteristics of pumpkin cultigens, number of total and marketable-quality fruit produced, and mean fruit weight in 1996 and 1997.z No. fruit/9.7-m rowy Mean fruit wt Days to Fruit Vine Cultivar Total Marketable (kg)y Cultivar maturityx sizew typev type 1996 1997 1996u 1997t 1996 1997 Appalachian 95 L Vine Hybrid 0.1 cds 4.1 d–i 0.0 0.9 f–i 0.86 b–g 7.4 c–f Autumn Gold 115 S Vine Hybrid 0.0 d 0.1 j–l 0.0 0.0 j ---r 2.4 j–m Big Autumn 85 M Semi Hybrid 0.1 cd 0.0 l 0.0 0.0 j 1.59 a–d --- Big Max 120 L Vine OPq 1.3 a–d 5.2 c–g 0.0 0.7 g–j 2.22 ab 22.1 a Connecticut Field 95 L Vine OP 1.3 a–d 3.5 e–j 0.9 0.3 h–j 0.54 d–j 8.7 b–e Funny Face 100 M Semi Hybrid 3.2 a–d 1.7 f–l 2.2 0.9 e–i 1.14 a–f 3.2 h–k Ghost Rider 115 M Semi OP 0.1 cd 4.7 c–h 0.0 3.7 b–d 0.28 h–j 4.8 f–h HMX 6686 100 L Vine Hybrid 10.2 a 23.9 a 2.7 7.1 b 1.06 a–f 5.3 e–h HMX 6688 110 S Vine Hybrid 2.1 a–d 2.8 f–k 0.9 0.7 g–j 0.43 e–j 2.6 i–l Happy Jack 100 M Vine OP 0.0 d 0.9 f–l 0.0 0.1 ij --- 5.3 e–h Howden 95 L Vine OP 0.3 cd 2.6 f–k 0.4 1.2 c–i 0.77 b–h 6.2 d–g Howden Biggie 120 L Vine OP 0.1 cd 0.3 j–l 0.0 0.0 j 1.05 a–f 9.9 b–d Jack of All Trades 105 M Semi Hybrid 0.3 cd 0.5 h–l 0.4 0.1 ij 0.55 d–i 2.0 k–m Jackpot 120 M Semi Hybrid 0.1 cd 0.4 i–l 0.0 0.0 j 0.53 e–j 7.3 c–f Little Lantern 90 S Vine OP 1.8 a–d 5.2 c–g 0.0 3.9 bc 0.19 ij 1.1 n Lumina 115 M Vine OP 0.3 cd 0.1 kl 0.9 0.1 ij 0.67 c–h 3.0 h–l Magic Lantern 110 L Vine Hybrid 3.7 a–d 12.3 a–d 0.9 3.6 b–d 0.72 c–h 6.1 d–g Mammoth Gold 115 L Vine OP 5.7 a–c 10.9 b–e 0.0 1.1 c–i 2.80 a 15.0 c–f Oz 110 S Semi Hybrid 2.5 a–d 1.8 f–l 1.3 0.4 h–j 0.29 g–j 1.7 l–n Pankow’s Field 110 M Vine OP 0.6 b–d 3.4 e–j 0.4 1.0 d–i 0.66 c–g 4.2 g–i Pro Gold 500 90 M Vine Hybrid 0.3 cd 1.4 f–l 0.4 0.3 h–j 1.25 a–e 3.3 h–k Pro Gold 510 90 M Vine Hybrid 0.1 cd 0.6 g–l 0.0 0.3 h–j 0.58 c–h 5.9 d–g Rocket 110 M Vine Hybrid 0.6 b–d 1.7 f–l 0.4 0.4 h–j 0.66 c–h 4.0 g–j Rouge Vif d’Etamps 115 L Vine OP 8.4 ab 12.7 a–c 0.0 0.9 f–i 1.71 a–c 12.6 bc Small Sugar 110 S Vine OP 0.6 b–d 5.3 c–f 0.6 3.5 b–e 0.57 d–h 1.3 mn Spirit 115 M Semi Hybrid 0.3 cd 0.5 h–l 0.0 0.0 j 0.18 j 2.6 i–l Spookie 95 S Vine OP 3.3 a–d 21.4 ab 1.3 12.9 a 0.30 g–j 2.0 k–m Spooktacular 100 S Vine Hybrid 5.9 a–c 6.0 c–f 5.3** 3.2 b–f 0.39 f–j 1.8 l–n Tallman 90 M Vine OP 0.3 cd 4.6 c–h 0.0 1.9 c–h 1.02 a–f 10.3 b–d Tom Fox 95 M Vine OP 0.0 d 5.0 c–g 0.0 3.0 c–g --- 3.7 g–j Trickster 85 S Semi OP 1.8 a–d 0.5 h–l 3.5 0.3 h–j 0.34 g–j 1.8 l–n Wizard 115 M Semi Hybrid 0.3 cd 5.6 c–f 0.0 1.1 c–i 0.67 c–h 3.8 g–j zCultigen × year interaction significant at P ≤ 0.01. yMeans for three replications in 1996 and four replications in 1997. xExpected days to maturity based on seed company descriptions. wFruit size, S = expected mean fruit weight <4.5 kg, M = expected mean fruit weight ≥4.5 kg but <9.1 kg, and L = mean fruit weight >9.1 kg, based on seed company descriptions. vVine = vining plant type, semi = semi-bush type of plant, based on field observations. uFruit with no decay, intact stems, and no disfiguration or color-breaking due to virus. tFruit with no decay, intact stems, and <20% surface area with virus symptoms. sMean separation by Waller–Duncan k ratio t test; k = 500 (approximates P = 0.01). rNo fruit produced in this year. qOpen-pollinated. **Only value significantly different from 0.0 in 1996, Dunnett’s t test, P ≤ 0.01.

HORTSCIENCE, VOL. 35(2), APRIL 2000 283 BREEDING, CULTIVARS, ROOTSTOCKS, & GERMPLASM RESOURCES years (Table 3). However, the number of mar- Table 3. Comparison of numbersz of total and marketable fruit in 1996 and 1997 by different classes of 26 ketable fruit did not differ significantly be- Cucurbita pepo and four C. maxima pumpkin cultigens. tween the two species. On average, long- and P > F valuey mid-season cultigens of both species produced Total fruit no. Marketable fruit no. greater numbers of total and marketable fruit x than did short-season cultigens, except for Contrast 1996 1997 1996 1997 long-season cultigens in 1996 (Table 3). Small- C. maxima and C. pepo cultigens C. maxima vs. C. pepo 0.0052 0.0091 0.11 0.17 fruited cultigens produced more total and mar- Vine vs. semi-bush 0.20 0.0001 0.84 0.0001 ketable fruit than did cultigens with medium- Open-pollinated vs. hybrid 0.78 0.0025 (0.023)w 0.0011 sized fruit both years. Likewise, cultigens with Long-season vs. short-seasonv 0.049 0.0001 0.20 0.0001 large fruit produced more fruit than did culti- Midseason vs. short-seasonv 0.022 0.0001 0.14 0.0001 gens with medium-sized fruit, except for mar- Large-fruited vs. medium-fruitedu 0.003 0.0001 0.22 0.005 ketable fruit of both species in 1996. However, Small-fruited vs. medium-fruitedu 0.006 0.002 0.0007 0.0001 number of marketable fruit generally did not C. pepo cultigens only Vine vs. semi-bush 0.54 0.0001 0.85 0.0001 differ between small- and large-fruited culti- w gens (data not shown). Vining cultigens pro- Open-pollinated vs. hybrid 0.14 0.025 (0.069) 0.0001 Long-season vs. short-season 0.46 0.0001 0.47 0.0001 duced more fruit than did semi-bush cultigens Midseason vs. short-season 0.027 0.0002 0.035 0.0001 in 1997, but not in 1996. Open-pollinated Large-fruited vs. medium-fruited 0.007 0.0001 0.057 0.006 cultivars produced more fruit than did hybrid Small-fruited vs. medium-fruited 0.001 0.0007 0.0007 0.0001 cultigens in 1997 but not in 1996. zNumber of fruit per 9.7-m row. Means for three replications in 1996 and four replications in 1997. yProbability that the mean for the class listed first was greater than the mean for the second class. Discussion xPreplanned single-degree-of-freedom contrasts. wThe mean for the class listed second was greater than the mean for the first class. In general, all four C. maxima cultivars and vLong-, mid-, and short-season are 110–120, 100–105, and 85–95 d to maturity, respectively. the three C. pepo cultigens with powdery uLarge-fruited = expected average fruit weight >9.1 kg, medium = ≥4.5 kg but <9.1 kg, and small = <4.5 kg. mildew resistance exhibited significantly lower powdery mildew severities than did suscep- Similarly, we detected PRSV, WMV, and short-season cultigens in these tests, they may tible C. pepo cultivars. These results were ZYMV in 1996 but only PRSV and ZYMV in have been exposed at transplanting to virus or consistent in both years, even though powdery 1997. Apparently, PRSV is one of the most powdery mildew inoculum from the earlier- mildew was more severe in 1996 than in 1997. common cucurbit viruses, whereas incidence planted cultigens. Cultigens with small (<4.5 When tested in other locations, ‘Magic Lan- of ZYMV and WMV can vary by year and kg) or large (≥9.1 kg) fruit produced greater tern’ (HMX 5683) and HMX 6686 also had location. As noted by Schultheis and Walters numbers of fruit than cultigens with medium- less powdery mildew than standard suscep- (1998), cultivars with resistance to PRSV are sized fruit (≥4.5 but <9.1 kg). The lower yields tible cultivars (McGrath, 1998; McGrath and needed to improve marketable yields of fall- of cultivars with medium-sized fruit may be Sieczka, 1997; Straw et al., 1998). We found grown cucurbits in the southeastern United States. explained partially by vining type, since seven the resistance of HMX 6688 to be as effective In , fruit expression of virus of the nine medium-fruited cultivars were semi- as the other two powdery mildew-resistant symptoms did not appear to be related to the bush types that, as a group, had lower yields lines we tested, as reported by McGrath and severity of foliar symptoms (Schultheis and than vining types in 1997. In addition, all five Sieczka (1997). However, in Ohio ratings for Walters, 1998). Similarly, ‘Small Sugar’ and top-yielding cultigens, Spookie, HMX 6686, HMX 6688 were not significantly different ‘Little Lantern’ pumpkin had good yields of Spooktacular, Magic Lantern, and Small Sugar, from ratings for ‘Jackpot,’ which is suscep- marketable-quality fruit, even though leaf are vining types. In 1997, 13 of the 32 culti- tible to powdery mildew (Precheur et al., 1998). symptoms of virus were severe. In contrast, gens tested produced fruit that reached the Because ‘Spookie’ had good marketable yields although the C. maxima cultivars had fewer expected sizes, whereas 14 produced fruit that despite high levels of powdery mildew, it may foliar virus symptoms than C. pepo cultigens, were smaller than expected. Only two C. pepo have some tolerance to this pathogen. most of the fruits graded as unmarketable had cultivars, ‘Howden Biggie’ and ‘Tallman’, Although we did not evaluate cultivars color-breaking and disfiguration typical of produced large fruit (≥9.1 kg) and neither of without applying fungicides, reducing the virus infection (Zitter et al., 1996). The two these cultivars had high yields. amount or frequency of fungicides applied to cultivars with the Py gene, ‘Big Autumn’ and Based on these 2 years of testing in one pumpkin cultivars with resistance to powdery ‘Autumn Gold’, produced few fruit, some of location, none of the 32 cultivars we examined mildew may be possible, as has been done which still showed color-breaking due to vi- were particularly well-adapted for production successfully with resistant summer squash rus. Powdery mildew severity also was not in the southeastern coastal plain, very likely cultivars (McGrath, 1996). A cultural control statistically correlated with marketable yield because no cultivar combines resistances to to supplement fungicidal control of powdery of fruit, probably because downy mildew and powdery mildew, downy mildew, PRSV, mildew is needed, since in many areas of the virus also reduced yields. ZYMV, and WMV. The two best-yielding United States the fungus is resistant to benomyl Yields of total and marketable fruit were cultivars were ‘Spooktacular’ and ‘Magic Lan- and triadimefon, the two most widely-used greater in 1997 than in 1996. Most cultivars tern’. Although ‘Spookie’ had a higher mean systemic fungicides effective against pow- seemed to require more than the 1.8-m spacing marketable yield (8.4 fruit per 9.7-m row of dery mildew on cucurbits (McGrath et al., allowed in 1996, and turning the fragile vines eight plants) over the 2 years than did 1996). However, powdery mildew-resistant damaged them, possibly reducing yields. Plant ‘Spooktacular’ (4.5 fruit), ‘Spooktacular’ had cultivars cannot be grown without fungicides, spacing of 0.9 m within rows in 1996 also may a much lower variance (20.0 compared with based on trials conducted in Ohio (Precheur et have been too close for optimum yields. In 85.4), indicating that it was a more reliable al., 1998) and New York (McGrath, 1998). addition, downy and powdery mildew pres- producer. ‘Spooktacular’ produced small fruit, Without fungicide, ‘Magic Lantern’ had less sure was higher earlier in the season in 1996 suitable for “pick-your-own” and other direct powdery mildew than a related susceptible than in 1997, which probably reduced yields markets. ‘Magic Lantern,’ which is resistant to experimental line, but more than the same line as well. Using lower rates of fungicides for powdery mildew, produced medium-sized that was sprayed with fungicide (McGrath, most of the 1996 season may have contributed fruit, suitable for both direct and wholesale 1998). to the higher disease pressure. markets. Because few cultivars yielded well In North Carolina, PRSV and WMV were As a group, short-season cultigens (<95 d under the hot, humid conditions, there is a need detected on summer squash one year, whereas to maturity) had lower total and marketable to develop pumpkin cultivars that are adapted PRSV, WMV, and ZYMV were detected the yields than did mid- or long-season cultigens. to production in the lower coastal plains of the following year (Schultheis and Walters, 1998). Because of the later transplanting date used for southeastern United States.

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